{"id":105601,"date":"2022-11-16T21:37:02","date_gmt":"2022-11-16T19:37:02","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/dve-uyazvimosti-v-grub2-pozvolyayushhie-obojti-zashhitu-uefi-secure-boot"},"modified":"2022-11-16T21:37:02","modified_gmt":"2022-11-16T19:37:02","slug":"dve-uyazvimosti-v-grub2-pozvolyayushhie-obojti-zashhitu-uefi-secure-boot","status":"publish","type":"post","link":"https:\/\/prohoster.info\/da\/blog\/news\/dve-uyazvimosti-v-grub2-pozvolyayushhie-obojti-zashhitu-uefi-secure-boot","title":{"rendered":"To s\u00e5rbarheder i GRUB2, der muligg\u00f8r omg\u00e5else af UEFI Secure Boot","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"<p>Oplysninger om to s\u00e5rbarheder i GRUB2-bootloaderen er blevet afsl\u00f8ret, som kan f\u00f8re til udf\u00f8relse af kode ved brug af specielt formaterede skrifttyper og behandling af bestemte Unicode-sekvenser. S\u00e5rbarhederne kan udnyttes til at omg\u00e5 mekanismen for verificeret opstart UEFI Secure Boot.        <\/p>\n<p>Identificerede s\u00e5rbarheder:  <\/p>\n<ul>\n<li class=\"l\"> CVE-2022-2601 \u2014 buffer overflow in the function grub_font_construct_glyph() when processing specially formatted fonts in pf2 format, caused by incorrect calculation of the max_glyph_size parameter and allocation of a memory area deliberately smaller than required to accommodate the glyphs.\n<li class=\"l\"> CVE-2022-3775 \u2014 out-of-bounds memory write when rendering certain Unicode sequences with specially formatted fonts. This issue exists in the font processing code and is caused by the lack of proper checks for the width and height of the glyph against the size of the available bitmap. An attacker could potentially craft input to trigger a write beyond the limits of the allocated buffer. It is noted that despite the complexity of exploiting the vulnerability, there is no exclusion of the possibility of code execution.                <\/ul>\n<p> Fixet er blevet offentliggjort som en patch. Status for s\u00e5rbarhedslukning i distributioner kan vurderes p\u00e5 disse sider: Ubuntu, SUSE, RHEL, Fedora, Debian. For at l\u00f8se problemerne i GRUB2 er det ikke tilstr\u00e6kkeligt blot at opdatere pakken, det er ogs\u00e5 n\u00f8dvendigt at lave nye interne digitale signaturer og opdatere installat\u00f8rer, bootloaders, kernelpakker, fwupd-firmwares og shim-lag.       <\/p>\n<p>I de fleste Linux-distributioner anvendes et lille shim-lag, der er digitalt signeret af Microsoft, til verificeret boot i UEFI Secure Boot-tilstand. Dette lag verificerer GRUB2 med sit eget certifikat, hvilket g\u00f8r det muligt for distributionsudviklere ikke at skulle signere hver opdatering af kernen og GRUB i Microsoft. S\u00e5rbarheder i GRUB2 tillader eksekvering af egen kode efter en vellykket verifikation af shim, men f\u00f8r operativsystemet er indl\u00e6st, ved at tr\u00e6nge ind i tillidsk\u00e6den under aktiv Secure Boot-tilstand og f\u00e5 fuld kontrol over den fortsatte bootproces, herunder nedl\u00e6sning af et andet OS, \u00e6ndring af komponenter i operativsystemet og omg\u00e5else af Lockdown-beskyttelsen.     <\/p>\n<p>For at blokere s\u00e5rbarheden uden at tilbagekalde den digitale signatur kan distributionerne anvende mekanismen SBAT (UEFI Secure Boot Advanced Targeting), som underst\u00f8ttes af GRUB2, shim og fwupd i de fleste popul\u00e6re Linux-distributioner. SBAT er udviklet i samarbejde med Microsoft og indeb\u00e6rer tilf\u00f8jelse af metadata til UEFI-komponenternes eksekverbare filer, som inkluderer oplysninger om producent, produkt, komponent og version. De n\u00e6vnte metadata signeres digitalt og kan separat inkluderes i lister over tilladte eller forbudte komponenter til UEFI Secure Boot.      <\/p>\n<p>SBAT g\u00f8r det muligt at blokere brugen af den digitale signatur for specifikke versionsnumre af komponenter uden at skulle tilbagekalde n\u00f8glerne til Secure Boot. Blokering af s\u00e5rbarheder gennem SBAT kr\u00e6ver ikke brugen af en liste over tilbagekaldte UEFI-certifikater (dbx), men udf\u00f8res p\u00e5 niveauet for udskiftning af den interne n\u00f8gle til dannelse af signaturer og opdatering af GRUB2, shim og andre boot-artifakter, der leveres af distributionerne. Inden SBAT blev indf\u00f8rt, var opdatering af listen over tilbagekaldte certifikater (dbx, UEFI Revocation List) en obligatorisk betingelse for fuld blokering af s\u00e5rbarheden, da en angriber, uanset hvilken operativsystem der blev brugt, kunne bruge en bootbare enhed med en gammel, s\u00e5rbar version af GRUB2, signeret med et digitalt certifikat, til at kompromittere UEFI Secure Boot.<br \/>\n<br \/>Kilde: <a content=\"nofollow\" rel=\"nofollow\" href=\"https:\/\/www.opennet.ru\/opennews\/art.shtml?num=58130\">opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"<p>\u0420\u0430\u0441\u043a\u0440\u044b\u0442\u044b \u0441\u0432\u0435\u0434\u0435\u043d\u0438\u044f \u043e \u0434\u0432\u0443\u0445 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044f\u0445 \u0432 \u0437\u0430\u0433\u0440\u0443\u0437\u0447\u0438\u043a\u0435 GRUB2, \u043a\u043e\u0442\u043e\u0440\u044b\u0435 \u043c\u043e\u0433\u0443\u0442 \u043f\u0440\u0438\u0432\u0435\u0441\u0442\u0438 \u043a \u0432\u044b\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u044e \u043a\u043e\u0434\u0430 \u043f\u0440\u0438 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0438 \u0441\u043f\u0435\u0446\u0438\u0430\u043b\u044c\u043d\u043e \u043e\u0444\u043e\u0440\u043c\u043b\u0435\u043d\u043d\u044b\u0445 \u0448\u0440\u0438\u0444\u0442\u043e\u0432 \u0438 \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0435 \u043e\u043f\u0440\u0435\u0434\u0435\u043b\u0451\u043d\u043d\u044b\u0445 Unicode-\u043f\u043e\u0441\u043b\u0435\u0434\u043e\u0432\u0430\u0442\u0435\u043b\u044c\u043d\u043e\u0441\u0442\u0435\u0439. \u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u043c\u043e\u0433\u0443\u0442 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u044c\u0441\u044f \u0434\u043b\u044f \u043e\u0431\u0445\u043e\u0434\u0430 \u043c\u0435\u0445\u0430\u043d\u0438\u0437\u043c\u0430 \u0432\u0435\u0440\u0438\u0444\u0438\u0446\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u043e\u0439 \u0437\u0430\u0433\u0440\u0443\u0437\u043a\u0438 UEFI Secure Boot. \u0412\u044b\u044f\u0432\u043b\u0435\u043d\u043d\u044b\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438: CVE-2022-2601 &#8212; \u043f\u0435\u0440\u0435\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u0435 \u0431\u0443\u0444\u0435\u0440\u0430 \u0432 \u0444\u0443\u043d\u043a\u0446\u0438\u0438 grub_font_construct_glyph() \u043f\u0440\u0438 \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0435 \u0441\u043f\u0435\u0446\u0438\u0430\u043b\u044c\u043d\u043e \u043e\u0444\u043e\u0440\u043c\u043b\u0435\u043d\u043d\u044b\u0445 \u0448\u0440\u0438\u0444\u0442\u043e\u0432 \u0432 \u0444\u043e\u0440\u043c\u0430\u0442\u0435 pf2, \u0432\u043e\u0437\u043d\u0438\u043a\u0430\u044e\u0449\u0435\u0435 \u0438\u0437-\u0437\u0430 \u043d\u0435\u0432\u0435\u0440\u043d\u043e\u0433\u043e \u0440\u0430\u0441\u0447\u0451\u0442\u0430 [&hellip;]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-105601","post","type-post","status-publish","format-standard","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 5.0.3 - aioseo.com -->\n\t<meta name=\"description\" content=\"\u0420\u0430\u0441\u043a\u0440\u044b\u0442\u044b \u0441\u0432\u0435\u0434\u0435\u043d\u0438\u044f \u043e \u0434\u0432\u0443\u0445 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044f\u0445 \u0432 \u0437\u0430\u0433\u0440\u0443\u0437\u0447\u0438\u043a\u0435 GRUB2, \u043a\u043e\u0442\u043e\u0440\u044b\u0435 \u043c\u043e\u0433\u0443\u0442 \u043f\u0440\u0438\u0432\u0435\u0441\u0442\u0438 \u043a \u0432\u044b\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u044e \u043a\u043e\u0434\u0430 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som kan f\u00f8re til udf\u00f8relse af kode ved brug af specielt formaterede skrifttyper og behandling af bestemte Unicode-sekvenser.","canonical_url":"https:\/\/prohoster.info\/da\/blog\/news\/dve-uyazvimosti-v-grub2-pozvolyayushhie-obojti-zashhitu-uefi-secure-boot","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"da_DK","og:site_name":"ProHoster | \u041a\u0443\u043f\u0438\u0442\u044c \u043d\u0430\u0434\u0435\u0436\u043d\u044b\u0439 \u0445\u043e\u0441\u0442\u0438\u043d\u0433 \u0434\u043b\u044f \u0441\u0430\u0439\u0442\u043e\u0432 \u0441 \u0437\u0430\u0449\u0438\u0442\u043e\u0439 \u043e\u0442 DDoS, VPS VDS \u0441\u0435\u0440\u0432\u0435\u0440\u044b","og:type":"article","og:title":"\ud83e\udd47\u0414\u0432\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u0432 GRUB2, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0438\u0435 \u043e\u0431\u043e\u0439\u0442\u0438 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